// Copyright 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/trees/tree_synchronizer.h"

#include <stddef.h>

#include <set>

#include "base/logging.h"
#include "base/trace_event/trace_event.h"
#include "cc/layers/layer.h"
#include "cc/layers/layer_collections.h"
#include "cc/layers/layer_impl.h"
#include "cc/trees/layer_tree.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"

namespace cc {

template <typename LayerTreeType>
void SynchronizeTreesInternal(LayerTreeType* source_tree,
    LayerTreeImpl* tree_impl,
    PropertyTrees* property_trees)
{
    DCHECK(tree_impl);

    TRACE_EVENT0("cc", "TreeSynchronizer::SynchronizeTrees");
    std::unique_ptr<OwnedLayerImplList> old_layers(tree_impl->DetachLayers());

    OwnedLayerImplMap old_layer_map;
    for (auto& it : *old_layers)
        old_layer_map[it->id()] = std::move(it);

    PushLayerList(&old_layer_map, source_tree, tree_impl);

    for (int id : property_trees->effect_tree.mask_layer_ids()) {
        std::unique_ptr<LayerImpl> layer_impl(ReuseOrCreateLayerImpl(
            &old_layer_map, source_tree->LayerById(id), tree_impl));
        tree_impl->AddLayer(std::move(layer_impl));
    }
}

void TreeSynchronizer::SynchronizeTrees(Layer* layer_root,
    LayerTreeImpl* tree_impl)
{
    if (!layer_root) {
        tree_impl->DetachLayers();
    } else {
        SynchronizeTreesInternal(layer_root->GetLayerTree(), tree_impl,
            layer_root->GetLayerTree()->property_trees());
    }
}

void TreeSynchronizer::SynchronizeTrees(LayerTreeImpl* pending_tree,
    LayerTreeImpl* active_tree)
{
    if (pending_tree->LayerListIsEmpty()) {
        active_tree->DetachLayers();
    } else {
        SynchronizeTreesInternal(pending_tree, active_tree,
            pending_tree->property_trees());
    }
}

template <typename LayerType>
std::unique_ptr<LayerImpl> ReuseOrCreateLayerImpl(OwnedLayerImplMap* old_layers,
    LayerType* layer,
    LayerTreeImpl* tree_impl)
{
    if (!layer)
        return nullptr;
    std::unique_ptr<LayerImpl> layer_impl = std::move((*old_layers)[layer->id()]);
    if (!layer_impl)
        layer_impl = layer->CreateLayerImpl(tree_impl);
    return layer_impl;
}

template <typename LayerTreeType>
void PushLayerList(OwnedLayerImplMap* old_layers,
    LayerTreeType* host,
    LayerTreeImpl* tree_impl)
{
    tree_impl->ClearLayerList();
    for (auto* layer : *host) {
        std::unique_ptr<LayerImpl> layer_impl(
            ReuseOrCreateLayerImpl(old_layers, layer, tree_impl));

        tree_impl->AddToLayerList(layer_impl.get());
        tree_impl->AddLayer(std::move(layer_impl));
    }
    tree_impl->OnCanDrawStateChangedForTree();
}

template <typename LayerType>
static void PushLayerPropertiesInternal(
    std::unordered_set<LayerType*> layers_that_should_push_properties,
    LayerTreeImpl* impl_tree)
{
    for (auto layer : layers_that_should_push_properties) {
        LayerImpl* layer_impl = impl_tree->LayerById(layer->id());
        DCHECK(layer_impl);
        layer->PushPropertiesTo(layer_impl);
    }
}

void TreeSynchronizer::PushLayerProperties(LayerTreeImpl* pending_tree,
    LayerTreeImpl* active_tree)
{
    PushLayerPropertiesInternal(pending_tree->LayersThatShouldPushProperties(),
        active_tree);
}

void TreeSynchronizer::PushLayerProperties(LayerTree* host_tree,
    LayerTreeImpl* impl_tree)
{
    PushLayerPropertiesInternal(host_tree->LayersThatShouldPushProperties(),
        impl_tree);
}

} // namespace cc
